Pearl works for the Resistance. She is a disguised angel, working as a flight attendant. Dr Kisi Sorle is personal physician to a tycoon who has despoiled Sorle’s native country. One day he happens upon what appears to be a briefcase. But this is clearly no ordinary briefcase: its weight is variable and it has hidden depths (literally, for sufficient meanings of ‘depth’) and it appears to eat people, or some aspect of them. The paths of Pearl and Sorle (but is it really him?) intersect catastrophically on a flight from New York to London.

This is an optimistic near-future novel where people are hijacked across different levels of reality. A SF thriller that plays with concepts such as Higher Dimensions and multiple universes.

The briefcase is indeed no ordinary case but a waveform launcher, a gateway to the Higher Dimensions (usually abbreviated to HD). Nobody is who they seem – quite literally, because one individual can have many trajectories, many possibilities, many aspects. An aspect of Pearl has been stolen and she wants it back.

The Resistance seeks to change the world by making small but significant changes, because this is what humans can/should be able to do: “if human beings didn’t want to find the magic,” says one character, “the shortcut, the underlying truth, then we wouldn’t have the big brains. We’d just have the big biceps.” Sullivan has stated her distaste for the laziness of dystopia elsewhere: hers is an optimistic world.

There are ghosts in the oil: ghosts of the creatures that died long ago and whose bodies went to make up the hydrocarbons – oil is relevant in all this, it’s the reason for the despoiling of Sorle’s native land and many others: “places that had been ruined by Pace Industries and the wars it funded, places left behind when people had packed up and moved away.”

“Occupy Me” is the name or designator of the briefcase (or what appears in our dimensions to be a briefcase). There’s a resonance with Alice in Wonderland here: “Eat Me, Drink Me.” And if you think about Alice and her mirror, the mirror is a flat plane but it reflects multi-dimensional worlds – both ours and the one she steps through into. The flat glass of the mirror has a similar relationship to that 3D world as our world does to the Higher Dimensions accessible to or via Occupy Me. Sometimes things come through the other way. There’s a whole Multiverse in there.

Despite Sullivan’s near-future Edinburgh being beset by a cynical megacorporation on the one hand and out-of-place animals on the other, it’s an affectionately-drawn society with memorable characters. The Bechdel Test (re female characters) is passed with confidence. The higher concepts introduced in this novel are brought in gradually and the novel remains grounded as a science fiction thriller, always readable and at the same time reaching for a palpable sense of wonder at the audacious possibilities hinted at.